Sometimes a passive crossover is just stupid...

[gberchin]

what's the purpose of putting batteries in it?

The amplifiers are powered by DC anyway, so why bother with an AC stage if it can be avoided?

 

[kyuu]

The amplifiers are powered by DC anyway, so why bother with an AC stage if it can be avoided?

Unless you have DC coming into your home you're going to have an "AC stage" somewhere. If you don't want to convert between AC and DC inside the device, you can do that externally without needing to introduce batteries into everything.

 

[gberchin]

Unless you have DC coming into your home you're going to have an "AC stage" somewhere.

Along with 60 Hz or 50 Hz hum, and all of the noise that's present in the powerlines. Folks spend large amounts on powerline conditioners, audiophile wall plugs, and exotic line cords, when pure DC power would solve all of those problems. No cords to the speakers except for the charging plug, and even that could conceivably be eliminated with removable battery packs, like your cordless drills, saws, and screwdrivers.

 

[bmc0]

Personally, I'd find better amplifiers. I recommend First Watt or other Nelson Pass single-stage FET designs

My amp has an output noise of around 30µV RMS (unweighted, 20Hz-20kHz), which is lower than the specs given for any of the First Watt amps aside from the F1 (30µV) and F2 (20µV). It's also capable of 50W into 8Ω rather than 10W or 5W.

The hiss is not exactly obtrusive at the listening position as-is (in fact, many recordings have a noticeably higher noise floor), but it is slightly audible without music playing and occasionally during very quiet passages (if the noise in the recording is low enough). The passive network I designed will reduce the hiss by ~10dB, which would be similar to using an amp with an output noise spec of ~10µV RMS (unweighted, 20Hz-20kHz). Such amps exist, of course, but aren't terribly common.

There are several DIY transconductance amplifier designs that can be used instead of heating resistors in series with acoustic drivers.

A typical transconductance amp has high output impedance over its entire bandwidth, but low driving impedance is actually an advantage at low frequencies. In the midrange, the dominant nonlinear distortion sources above H2 are usually flux modulation and hysteresis in the motor. High driving impedance improves these distortions. Around the LF resonance, however, excursion-related nonlinearities such as those shown by Bl(x) and Kms(x) tend to become significant. Low driving impedance provides feedback around resonance, which linearizes these effects.

 

[kyuu]

Along with 60 Hz or 50 Hz hum, and all of the noise that's present in the powerlines. Folks spend large amounts on powerline conditioners, audiophile wall plugs, and exotic line cords, when pure DC power would solve all of those problems.

Power supplies by design already solve all those problems. They're already capable of filtering out any actual issues and outputting "pure" DC. You don't need batteries for that.

No cords to the speakers except for the charging plug, and even that could conceivably be eliminated with removable battery packs, like your cordless drills, saws, and screwdrivers.

Sounds awful, honestly. For something that's not going to get moved around often, doesn't generally need to work when it is being moved, and will be consuming power for long periods of time, having to continually change batteries is about as big an unwanted and unnecessary hassle as I can imagine.

If you really want to do this, way more practical to just build yourself a DC power system at the voltage(s) you need and run wiring to the devices.

 

[gberchin]

Power supplies by design already solve all those problems.

There are people who would disagree with you.

Sounds awful, honestly.

You do what works for you.

 

[neRok]

I envision a day when each loudspeaker has only one cable attached to it -- a power cable to charge the batteries.

An all-digital signal is sent wirelessly to each loudspeaker, which is processed by an onboard DSP and sent to individual battery-powered Class-D amplifiers, one per driver.

In the pro-audio world there is the Dante network, which connects devices via ethernet cables. There's also consumer products out there that do ethernet over power (ie through the electrical network already in your walls). So really we just need a company to blend the 2 products together, and then 1 cable really will do everything

 

[MaxwellsEq]

There are people who would disagree with you

Then THEY must supply evidence to support their position.

 

[gberchin]

Then THEY must supply evidence to support their position.

Every person who has ever fought 60 Hz hum from a ground loop can provide that evidence.

 

[bmc0]

Alternatively, one could just use properly designed balanced inputs and outputs.

 

[SIY]

Every person who has ever fought 60 Hz hum from a ground loop can provide that evidence.

That's a grounding issue, not a power supply issue.

 

[gberchin]

Alternatively, one could just use properly designed balanced inputs and outputs.

That's a grounding issue, not a power supply issue.

Or one could use DC.

As I said before, you do what works for you. The fact that you do not agree with an idea does not invalidate it.

 

[SIY]

Or one could use DC.

As I said before, you do what works for you. The fact that you do not agree with an idea does not invalidate it.

"Using DC" will not obviate ground loops unless every piece of equipment is floating with battery supplies, hardly practical.

Alternatively, one could just use properly designed balanced inputs and outputs.

Now that will obviate ground loops. It is the correct solution, and far more practical to implement.

 

[Petrushka]

So what the world needs is a plate amp standard. Dimensions, connectors, etc.

 

[Ropeburn]

Along with 60 Hz or 50 Hz hum, and all of the noise that's present in the powerlines. Folks spend large amounts on powerline conditioners, audiophile wall plugs, and exotic line cords, when pure DC power would solve all of those problems.

You mean, like every half-proper PSU solves all these problems, and has been for what, 50 years?

For about as long as snake oil salesmen have been selling their "conditioners" to oblivious and clueless people? And 5000% markup "exotic cords"?

 

[kyuu]

Or one could use DC.

As I said before, you do what works for you. The fact that you do not agree with an idea does not invalidate it.

It's not about agreeing with or not. It's about what actually makes sense and will solve actual issues.

Getting good DC power to the components that need it is already a solved problem. That some people buy expensive cables to satisfy their ignorance and/or superstition does not obviate that fact. Also, you're moving the goalposts to ground loops, which as already stated has nothing to do with AC versus DC.

You're also ignoring that you still need AC in your audio circuit, unless you're planning to somehow reproduce the audible spectrum with a 0 Hz DC signal.

 

[gberchin]

Now that will obviate ground loops. It is the correct solution, and far more practical to implement.

Sure ... that's why these are still needed: https://www.sweetwater.com/store/detail/GLT255--hosa-glt-255

 

[gberchin]

It's about what actually makes sense and will solve actual issues.

You keep asserting that existing designs solve the issues. Yet hum and noise still exist on the DC outputs. It only takes one counterexample to disprove an assertion.

 

[gberchin]

You're also ignoring that you still need AC in your audio circuit, unless you're planning to somehow reproduce the audible spectrum with a 0 Hz DC signal.

So, the 60Hz/50Hz that enters the system is necessary to produce the AC audio signals? Then why bother converting it to DC in the power supply?

 

[Ropeburn]

So, the 60Hz/50Hz that enters the system is necessary to produce the AC audio signals? Then why bother converting it to DC in the power supply?

Please don't be like that, when you know very well what he meant. The DC supply is used to amplify an AC signal - aka music.